The paper presents two studies with 2 year-olds, 3 year-olds, and adults. The first study addresses the use of object history to determine ownership, while the second studies the endowment effect. The experimental design is very simple: assign objects (from certain object sets) to individuals, and then ask subjects a) which object belongs to whom, b) which object they like best.

1) Ownership is abstract… or nonobvious.

One a conceptual level, it is interesting that this paper emphasizes the fact that ownership is abstract. I have previously used that word, abstract, to refer to ownership in a recent paper of my own. But, actually, that’s not the word that Gelman et al. prefer to use when speaking of ownership; they describe it as nonobvious rather than abstract. Here’s what they say:

Ownership is of interest because it is a cognitive construction, not materially present in the owned object. As Snare (1972, p. 200) aptly stated, ‘‘[A] stolen apple doesn’t look any different from any other apple.’’

A mature concept of ownership includes an understanding that proximity, perceptual or functional features, and desirability, although potent factors, cannot by themselves determine who owns what. In other words, ownership is an invisible quality that can be traced by consideration of object history rather than by inspection of the properties of the object.

I don’t know why the talk about “nonobvious” rather than “abstract”. Abstract seems to be the common-sense word to describe invisible, relational features.

2) Object history.

In order to assess who owns what, human agents reconstruct the history of each individual object (“first I found it there, then I gave it to her, then she placed it in that red box… etc.). “Given the centrality of object history, it becomes particularly important to track where an object moves over time.”

“Experiment 1 demonstrates that 3-year-olds, like adults, construe ownership as a nonobvious property that does not reduce to outward perceptual or functional features”. “This doesn’t seem to be the case for 2-year-olds, who in certain experimental situations and with certain sets of objects do not seem to use object history in their ownership judgments.” “The present studies demonstrate that children as young as 3 years of age spontaneously attend to object history to determine ownership.”

3) Endowment effect

The authors claim that they are the first to demonstrate an endowment effect in children 2 and 3 years of age. “The present findings suggest that positive evaluation of and preference for one’s own possessions is a basic cognitive disposition, even before children have experience with conventional economic transactions.”

This is interesting. By the way, why do they say that the disposition to value one’s own stuff is “cognitive”? They call it a “cognitive disposition”. But you can make the case that such a basic way of being of humans and perhaps other species is not appropriately described as “cognitive”. We are dealing with something that is as emotional as it is cognitive. We value and defend what we are and what we have. This phenomenon (the endowment effect) might be linked even with territorial behaviors. I think there are deep existential, cultural and evolutionary motivations in this “will to possess” and to value what one has. The word “cognitive” would suggest a conceptual frame, an innate category, some “cold” rule or feature of our cognitive system. It’s not proved that that’s the best description of what’s going on here.

“Ownership confers special value on objects, across the life span. This finding extends beyond prior work in demonstrating that preference is for the particular object assigned (not just for that type of object).”

4) Endowment effect precedes object history tracking

“The most striking developmental change concerned the comparison between the two experiments. Three-year-olds and adults distinguish ownership from likability, reporting that they owned objects even when they did not like them (e.g., the participant-plain items). In contrast, 2-year-olds show no difference between the ownership task (Experiment 1) and the endowment task (Experiment 2). In other words, 2-year-olds conflate ownership with desirability, thus failing to grasp that a toy they do not like actually belongs to them.

5) Mutual exclusivity

“Participants showed a mutual exclusivity bias concerning ownership, rarely assigning an object to Zippy [a fictional character they introduced in some situations] that had already been assigned to another owner. Mutual exclusivity is a principle that young children adhere to in their word extensions (Markman, 1989; Markman, Wasow, & Hansen, 2003), and it is notable that this same principle applies outside the realm of labeling.”

One might speculate about mutual exclusivity as a common feature of ownership and language. Perhaps this is an innate rule or constraint of our cognitive system, that is applied to different domains as language and ownership? Or perhaps mutual exclusivity as a principle co-evolved with human society and the rules of ownership? There are theories that derive human’s symbolic functioning from social life, and in particular from the institution of ownership. Mutual exclusivity is essential for the institution of ownership: the very meaning of something being mine is that I, not you, control it; if something is mine it’s not yours. In order to claim something as your own, you need to put a mark on the object, or make a gesture, or use some other symbolic means, that might be at the very origin of the semiotic function in general and language in particular.